1. Field of the Invention
The invention relates in general to elevator systems, and more specifically to new and improved elevator supervisory control apparatus for directing a plurality of elevator cars to more efficiently serve the floors of a building.
2. Description of the Prior Art
Elevator systems which include a plurality of elevator cars, and supervisory control for directing the elevator cars to serve registered hall or floor calls according to a predetermined strategy, usually have special strategies for serving calls which originate from basement and top extension floors. A building may also have one or more special floors, other than the main floor, basement floors, and top extension floors, which are to be provided with special service for some reason. The special service may be necessary, for example, because this floor is served by fewer than the total number of elevator cars, such as by only one or two of the cars out of a bank of elevator cars. Since mid-extensions are normally served by less than the total number of elevator cars in a bank, such a floor is often referred to as a mid-extension floor.
When a hall call for elevator service is registered from this special floor, or specifically for this floor by a special button located remotely from this floor, the search for an in-service idle car capable of serving this floor should be given a fairly high priority over other demands for elevator service. This insures that when a car capable of serving this special floor becomes available for assignment, that it will be assigned to the special floor demand, rather than to demands which other elevator cars could also handle.
A floor may also be selected for special service, even when it is served by all of the elevator cars, in order to provide a higher priority for the demands related to this floor, than to demands from other intermediate floors in the building.
Since service for such special floors requires a special strategy, the special strategy should be selected such that it has as little adverse affect on the over-all quality of elevator service to the building as possible.